MEMORY DEVICE BASED ON HETEROSTRUCTURES OF FERROELECTRIC AND TWO - DIMENSIONAL MATERIALS

A ferroelectric random-access memory structure and processes for fabricating a ferroelectric random-access memory structure are described that includes using a molybdenum sulfide layer. In an implementation, a ferroelectric random access memory structure in accordance with an exemplary embodiment includes at least one FeFET, which further includes a substrate; a back gate electrode formed on the substrate, the back gate electrode including a conductive layer; a gate dielectric substrate formed on the back gate electrode; a source electrode formed on the gate dielectric substrate; a drain electrode formed on the gate dielectric substrate; and a layered transition metal dichalcogenide disposed on the gate dielectric substrate and contacting the source electrode and the drain electrode

MEMORY DEVICE BASED ON HETEROSTRUCTURES OF FERROELECTRIC AND TWO - DIMENSIONAL MATERIALS

A ferroelectric random-access memory structure and processes for fabricating a ferroelectric random-access memory structure are described that includes using a molybdenum sulfide layer. In an implementation, a ferroelectric random access memory structure in accordance with an exemplary embodiment includes at least one FeFET, which further includes a substrate; a back gate electrode formed on the substrate, the back gate electrode including a conductive layer; a gate dielectric substrate formed on the back gate electrode; a source electrode formed on the gate dielectric substrate; a drain electrode formed on the gate dielectric substrate; and a layered transition metal dichalcogenide disposed on the gate dielectric substrate and contacting the source electrode and the drain electrode

High-temperature electron hole liquid in diamond wires

The density functional theory is used to study the properties of the electron hole liquid (EHL) in diamond quantum wires. Take a quantum wire with a circular cross section with radius R. Electrons and holes move freely along the z-axis. To calculate the energy and equilibrium density of the EHL, the Schrödinger equations for electrons and holes are solved numerically. Calculations have shown that the EHL is stable in diamond wires with a radius of several exciton radii. As the radius of the quantum wire decreases, the equilibrium density increases and the EHL energy decreases. So, with the radius of the quantum wire equal to the exciton radius (1.38 nm), the equilibrium linear density and energy of the EHL can reach values of 2.2 ∙ 107 cm–1 and – 317 meV, respectively. Estimates show that for these values of density and energy, the critical temperature of the EHL is Tc ≈ 370 K

Semiclassical transition in \phi^4 theory

We have shown an example of semiclassical transition in $\phi^{4}$ theory with positive coupling constant. This process can be described by the classical $O(4)$-invariant solution, considered on a contour in the complex time plane. The transition is technically analogous to the one-instanton transition in the electroweak model. It is suppressed by the factor $\exp(-2S_{0})$, where $S_{0}$ is Lipatov instanton action. This process describes a semiclassical transition between two coherent states with much smaller number of particles in the initial state than in the final state. Therefore, it could be relevant to the problem of calculation of amplitudes for multiparticle production in $\phi^4$-type models.Comment: 26 pages, JHU-TIPAC-930013, (correct 2 typos, some notations

Saturn Neutron Exosphere as Source for Inner and Innermost Radiation Belts

Energetic proton and electron measurements by the ongoing Cassini orbiter mission are expanding our knowledge of the highest energy components of the Saturn magnetosphere in the inner radiation belt region after the initial discoveries of these belts by the Pioneer 11 and Voyager 2 missions. Saturn has a neutron exosphere that extends throughout the magnetosphere from the cosmic ray albedo neutron source at the planetary main rings and atmosphere. The neutrons emitted from these sources at energies respectively above 4 and 8 eV escape the Saturn system, while those at lower energies are gravitationally bound. The neutrons undergo beta decay in average times of about 1000 seconds to provide distributed sources of protons and electrons throughout Saturn's magnetosphere with highest injection rates close to the Saturn and ring sources. The competing radiation belt source for energetic electrons is rapid inward diffusion and acceleration of electrons from the middle magnetosphere and beyond. Minimal losses during diffusive transport across the moon orbits, e.g. of Mimas and Enceladus, and local time asymmetries in electron intensity, suggest that drift resonance effects preferentially boost the diffusion rates of electrons from both sources. Energy dependences of longitudinal gradient-curvature drift speeds relative to the icy moons are likely responsible for hemispheric differences (e.g., Mimas, Tethys) in composition and thermal properties as at least partly produced by radiolytic processes. A continuing mystery is the similar radial profiles of lower energy (<10 MeV) protons in the inner belt region. Either the source of these lower energy protons is also neutron decay, but perhaps alternatively from atmospheric albedo, or else all protons from diverse distributed sources are similarly affected by losses at the moon' orbits, e.g. because the proton diffusion rates are extremely low. Enceladus cryovolcanism, and radiolytic processing elsewhere on the icy moon and ring surfaces, are additional sources of protons via ionization and charge exchange from breakup of water molecules. But one must then account somehow for local acceleration to the observed keV-MeV energies, since moon sweeping and E-ring absorption would remove protons diffusing inward from the middle magnetosphere. Although the main rings block further inward diffusion from the inner radiation belts, the exospheric neutron-decay source, combined with much slower diffusion of protons relative to electrons, may produce an innermost radiation belt in the gap between the upper atmosphere and the D-ring. This innermost belt will first be explored in-situ during the final proximal orbits of the Cassini mission

All Two-Loop MHV Amplitudes in Multi-Regge Kinematics From Applied Symbology

Recent progress on scattering amplitudes has benefited from the mathematical technology of symbols for efficiently handling the types of polylogarithm functions which frequently appear in multi-loop computations. The symbol for all two-loop MHV amplitudes in planar SYM theory is known, but explicit analytic formulas for the amplitudes are hard to come by except in special limits where things simplify, such as multi-Regge kinematics. By applying symbology we obtain a formula for the leading behavior of the imaginary part (the Mandelstam cut contribution) of this amplitude in multi-Regge kinematics for any number of gluons. Our result predicts a simple recursive structure which agrees with a direct BFKL computation carried out in a parallel publication.Comment: 20 pages, 2 figures. v2: minor correction

Compositional Impact of Io Volcanic Emissions on Jupiter's Magnetosphere and the Icy Galilean Moons

The magnetospheric ion population of Jupiter is dominated by the 1000 kg/s of iogenic material constantly ejected by IO volcanism as neutral gas (approx. 1 kg/s goes out as high speed dust grains), subsequent atmospheric losses to the IO torus, and radial transport of torus ions throughout the magnetosphere. As that magnetosphere is greatly distended in radial size by the iogenic plasma loading, so are surfaces of the other Galilean moons also significantly, and perhaps even dominantly, affected by iogenic plasma bombardment, e.g. at the level up to 0.2 kg/s heavy ions (mostly O and S) onto Europa as per local plasma ion measurements. In comparison, cometary impacts onto IO deliver about 0.02 kg/s of impact ejecta to Europa via ballistic transfer through the Jupiter system. The magnetosphere of this system operates as a powerful engine to produce and transport ions from the IO source to the surfaces of these other moons, and any future orbiter missions to these moons must account for surface distributions of the iogenic material and its chemical effects before real assessments can be made of sensible chemical materials otherwise arising from primordial formation and subsequent evolution of these moons. This is a fundamental problem of space weathering that must be addressed for all planetary bodies with thin atmospheres and direct surface exposure to their space plasma environments. Long-standing debates from Galileo Orbiter measurements about the origins of hydrate sulfates at Europa present examples of this problem, as to whether the sulfates arise from oceanic minerals or from iogenic sulfur chemistry. Any orbiter or landed mission to Europa for astrobiological investigations would further need to separate the potential chemical biosignatures of life or its precursors from the highly abundant background of iogenic material. Although no single ion carries a tag identifying it as of iogenic or other origin, the elemental abundance distributions of ions to be measured throughout the jovian magnetosphere and in the local moon environments can act as tracers if we know from direct measurements and models the distributions at the mostly likely sources, i.e. at IO. However, our knowledge of these abundances are very limited from earlier in-situ and remote measurements, mainly confined to major (S, O) and some minor (Na, K, Cl) species with abundances at or above a few percent relative to O. Future in-situ plasma measurements by the planned Jupiter Europa Orbiter and Jupiter Ganymede Orbiter missions should extend the abundance coverage to minor and even trace elemental species. For Europa astrobiological investigations it is also important to specify iogenic inputs and surface processing of isotopic species. We discuss the range of abundance distributions arising from models for IO hot volcanic emissions, and from the subsequent dynamics of ion injection, magnetospheric transport, and icy moon surface bombardment

What happens when transition metal trichalcogenides are interfaced with gold?

Transition metal trichalcogenides (TMTs) are two-dimensional (2D) systems with quasi-one-dimensional (quasi-1D) chains. These 2D materials are less susceptible to undesirable edge defects, which enhances their promise for low-dimensional optical and electronic device applications. However, so far, the performance of 2D devices based on TMTs has been hampered by contact-related issues. Therefore, in this review, a diligent effort has been made to both elucidate and summarize the interfacial interactions between gold and various TMTs, namely, In4Se3, TiS3, ZrS3, HfS3, and HfSe3. X-ray photoemission spectroscopy data, supported by the results of electrical transport measurements, provide insights into the nature of interactions at the Au/In4Se3, Au/TiS3, Au/ZrS3, Au/HfS3, and Au/HfSe3 interfaces. This may help identify and pave a path toward resolving the contemporary contact-related problems that have plagued the performance of TMT-based nanodevices

NV−^{-} Diamond Laser

For the first time, lasing at NV$^{-}$ centers in an optically pumped diamond sample is achieved. A nanosecond train of 150-ps 532-nm laser pulses was used to pump the sample. The lasing pulses have central wavelength at 720 nm with a spectrum width of 20 nm, 1-ns duration and total energy around 10 nJ. In a pump-probe scheme, we investigate lasing conditions and gain saturation due to NV$^{-}$ ionization and NV$^{0}$ concentration growth under high-power laser pulse pumping of diamond crystal

Electron hole liquid in diamînds formed by nanosecond laser pulses

Electron-hole liquid (EHL) is a condensed state of non-equilibrium charge carriers, which can exist in some semiconductor materials at low temperature and high carrier density. Phenomenon of EHL is a promising thing for development of diamond based electronic devices, such as opto-electronical switches. Earlier in our paper [1] we showed that the presence of EHL strongly increases the photoconductivity of diamond sample